<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>后代选择器</title>
    <style>
        .card .item {
          color: red;
          font-weight: bold;
        }
        
        .item {
          color: black;
          font-weight: normal;
        }
      </style>
    </head>
    <body>
      <div class="card">
        <div class="meta">
          <span class="item">这个文字会变红加粗（在.card内）</span>
        </div>
      </div>
      

      <div class="other">
        <span class="item">这个文字保持黑色（不在.card内）</span>
      </div>
    </body>
    </html>
    